Mega spam-spewing Grum botnet finally KO'd

Security researchers have dealt a knockout blow to Grum, one of the most prolific spam-distribution botnets.

Command-and-control servers in the Netherlands were taken out on Monday, but that still left zombie control nodes in Russia and Panama up and running. According to security researchers, pressure was applied on a Panamanian ISP hosting a botnet-linked server to clean up its act or risk losing upstream connectivity. The tactic worked by Tuesday, apparently, but that still left the Russian motherlode as well as secondary command servers hosted in Ukraine, a country that's been something of a safe haven for cybercrime in the past.

According to researchers, after some lobbying, the plug was pulled on the Ukrainian hosted servers. Meanwhile, action by an upstream provider null-routed the Russian-hosted node, despite a reported unwillingness to heed complaints by GazInvestProekt, the local ISP.

"All the known command and control (CnC) servers are dead, leaving their zombies orphaned," Atif Mushtaq, a researcher at network security and malware intelligence firm FireEye, announced on Wednesday. FireEye worked with other security researchers at Spamhaus, the Russian Computer Security Incident Response Team and elsewhere on the takedown operation.

Grum was the world's third-biggest botnet and responsible for 18 per cent of global junk mail around the time of its takedown, or 18 billion spam messages a day. The zombie network has been around for around five years and most often associated with rogue pharmacy and fake Rolex spam. Estimates vary but the number of infected drones on its network may number 800,000 or more. The stream of crud is rapidly drying up, according to FireEye.

"According to data coming from Spamhaus, on average, they used to see around 120,000 Grum IP addresses sending spam each day, but after the takedown, this number has reduced to 21,505," Mushtaq writes. "I hope that once the spam templates expire, the rest of the spam will fade away as well."

The Grum takedown operation follows similar exercises against other junkmail distribution networks such as Srizbi, Rustock, Ozdok and Cutwail. The latest case is noteworthy because it showed that even ISPs within Russia and the Ukraine can be pressured to end their cooperation with bot herders. "There are no longer any safe havens," Mushtaq concluded. ®